1. Field of the Invention
This invention relates to a method for fabricating a patterned thin film and a micro device with the patterned thin film.
2. Related Art Statement
In the fabrication of a micro device with a patterned thin film, the patterned thin film is formed by utilizing a patterned resist mask. Herein, the xe2x80x9cmicro devicexe2x80x9d means a small-sized device formed by means of film-forming technique, and encompasses a semiconductor device, a thin film magnetic head, a sensor with a thin film, a actuator with a thin film and the like.
The patterned thin film is also formed by means of dry-etching (which is described as a milling patterning method in Patent Document 1), lift-off, the combination thereof or the like.
In the micro device such as the semiconductor device, the thin film magnetic head, the sensor and actuator with their respective thin films, on the other hand, it is strongly required to miniaturize the patterned thin film, along with to down-size the micro device and to develop the performances of the micro device. In order to satisfy the above-mentioned requirements, it is required to reduce the width and the thickness of a resist mask to be utilized in the fabrication of the patterned thin film.
In the fabrication of the patterned thin film by means of lift-off, in contrast, it becomes difficult to infiltrate a solvent around the resist mask to be removed as the thickness of the resist mask is decreased. As a result, the resist mask may be not removed perfectly, and thus, some flashed may remained.
In the fabrication of the patterned thin film by means of dry etching, some dry etched debris, which are exfoliated from the resist mask, may be attached to the boundaries between the resist mask and the patterned thin film under dry etching process, so that some flashes may remained after the removing process with a solvent. In the fabrication of the patterned thin film by means of the combination of the lift off and the dry etching, the similar flashes may be created after the removing process of resist mask.
In this way, if flashes remain after the removing process of resist mask, the quality and reliability of the intended micro device may be degraded and the production yield of micro device may be deteriorated.
[Patent document 1]
Japanese Patent Application Laid-open No. 9-96909
It is an object of the present invention to provide a method for fabricating a patterned thin film, whereby the resist mask can be removed without flashes, and a micro device with the patterned thin film.
For achieving the above objects, this invention relates to a method for fabricating a patterned thin film, comprising the steps of:
preparing a base,
forming a resist mask on the base,
forming a thin film via the resist mask to form a patterned thin film,
coating an organic resin with an optical crosslinking agent therein to form an organic resin layer over the resist mask and the patterned thin film,
crosslinking the organic resin layer, and
removing the resist mask and the organic resin layer.
In the crosslinking the organic resin layer with the optical cross-linking agent therein, exposure is carried out over the organic resin layer if the crosslinking agent is negative.
In the present invention, since the patterned thin film is formed on the base with the resist mask by means of dry etching, the dry etched debris may be attached over the resist mask and the boundaries between the resist mask and the patterned thin film under dry etching. As a result, some flashes remain after the removing process of resist mask with a solvent, as mentioned above. If the combination of lift-off and dry etching is employed to remove the resist mask, some flashes remain, as mentioned above.
In order to remove the flashes originated from the attachment of the dry etched debris, in the present invention, the organic resin layer with the crosslinking agent is formed over the resist mask and the patterned thin film, and then, crosslinked. With the dry etching, the resultant dry etched debris are trapped around the resist mask by the crosslinked organic resin layer. With the lift off, the resultant lifted-off debris are trapped around the resist mask by the crosslinked organic resin layer.
After the trapping of the debris with the crosslinked organic resin layer, the organic resin layer and the resist mask are removed. In the removal, the assembly under fabrication is immersed into an organic solvent and vibrated therein or irradiated by an ultrasonic wave.
According to the above-mentioned process, the resist mask can be removed without flashes.
The resist mask may be made of a single-layered resist mask or a multilayered resist mask. With the single-layered resist mask, no undercut portion is formed. With the multilayered resist mask, a top resist layer and a bottom resist layer are successively formed. Some undercut portions are formed at the bottom resist layer. The surface area of the top resist layer is set larger the surface area of the bottom resist layer. With the multilayered resist mask, the patterned thin film can be miniaturized easily due to the undercut portions of the bottom resist layer thereof.
In the present invention, the patterned thin film can be made by means of lift off, dry etching, the combination thereof or the like.
The fabricating method of patterned thin film of the present invention can be applied to the fabrication of a micro device. In this case, a given patterned thin film of the micro device is formed by the fabricating method of patterned thin film. As the micro device are exemplified a thin film magnetic head, a semiconductor device, a sensor with a thin film, an actuator with a thin film and the like. With the thin film magnetic head, a magnetoresistive effective element is composed of the resultant patterned thin film.